• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.364-369
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• 2012

Location information is a critical element of ubiquitous computing. Cricket is an indoor location-based system that transmits radio and ultrasonic signals in regular intervals to calculate the distance between nodes. However, the amount of signal interference and collisions increases in proportion with the number of nodes, losing the accuracy of the location-based system. This study proposes an algorithm based on the 802.15.2 MAC protocol for the wireless sensor network to reduce signal interference and collision by employing node numbers and the frequency reuse approach used in mobile telecommunication. We analyzed the performance of our algorithm. The obtained results showed that the algorithm is an effective for throughput and energy compared to the Cricket system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3028-3039
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• 2015

Recently, the web index of Korea peaked at the top 10 among the eighty six countries, and Korea became the only Asian country ranked at the top level. Korea also has been on the top in the field of Internet penetration rate, in terms of both high-speed broadband and wireless Internet. However, such achievements did not guarantee the national level for the effective use of information utilizing Internet. According to OECD, the national informatization index of Korea has not been free from the middle of the OECD countries. Despite of the heightened pressure in practically enhancing effective information use utilizing Internet, the previous research interests and efforts to develop the Internet-related framework or to identify Internet capabilities rarely existed. The study aims to propose the framework, named "Internet Information Orientation" that illustrates the relationship between Internet capabilities and national competitiveness on Internet. The research identified the specific Internet capabilities, reclassified the capabilities based on the research issues provided at the 6^th international conference on Internet held in December 2014, and finally described the rigorous research endeavors on the issues. As a result, 16 papers presented and selected as the outstanding papers at the conference handle issues to be brought together, which include: Wireless Network, Internet of Things, Green Computing, Multimedia Processing, Big Data and Text Mining, Database in Cloud Environment, Business Intelligence, Software Engineering, IT Strategy & Policy, and Social Network Services.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.97-101
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• 2008

Voice over IP is a telephone service which sends and receives the voices through the Internet. Because the infrastructure of wireless and mobile communication networks such as 3G, Wi-Fi and WiMAX has expanded, the study about Mobile VoIP, which provides the voice service from wireless network, has been actively in progress. Since Rei 6 HSPA in 3GPP and Rev A lxEVDO in 3GPP2, VoIP through the data channel is more efficient than circuit switch. It is predicted that VoIP over 4G will be more effective and 4G mobile VoIP business will be vitalized in the future. In addition, there are businesses which offer VoWLAN by using software such as Skype and Fring. They provide services which cheapen the price of international calls and long distance calls. This paper will present the Korean and other countries' mobile VoIP trends, its classification along the network connection, the study on techniques, and conditions of mobile VoIP. It also will be described a view of terminal convergence and service convergence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.271-276
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• 2009

An local area weather condition monitoring system to minimize many disasters from the sudden change of weather condition in local and mountain area is proposed. Firstly, the comparison of present state of the related monitoring systems and the possibility of realization with some merits are investigated. Moreover, this paper present direction of local area weather condition monitoring system based on integration of wireless sensor network and CDMA network following some case study. Through the efficient integration of both networks, the measured weather condition data from sensors can be transmitted to the server or mobile to monitor with high reliability. The proposed monitoring system will guide new type of project in wireless sensor network and support alarm service of the sudden change of weather condition to mobile user from central official regulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2107-2112
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• 2006

As growing up of elderly population, the interesting on healthcare system in normal life using W is increasing. An integrated u-healthcare service architecture with IEEE 802.11 and IEEE 802.15.4 based sensor network and code divisi(m multiple access(CDMA) public mobile telecommunication networks was designed and developed. Sensor nodes with electrocardiogram(ECG), body core temperature sensors are attached on the patients' body. The healthcare parameters are transferred to web server via CDMA mobile network or through existed LAN network. The existed LAN network is suggested to be used for continuous monitoring of patient's health status in hospital while mobile networks can be used for general purpose at home or outdoor where infra networks unavailable. This system enable healthcare personal to be able to continuously access, review, monitor and transmit the patients information whereever they are, whenever they want. And immediately check their status by using cellular phone and obtain detail information by communication with medical information server through CDMA. By using this developed integrated u-healthcare service architecture, we can monitor patients' health status for 24 hours.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.607-612
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• 2006

Universal Mobile Telecommunications System (UMTS) and Wireless Local Area Network (WLAN) have been developed independently. Then, many researchers have studied UMTS-WLAN interworking architecture for the efficiency. However, the transmission capacity difference of two networks causes the transmission quality degradation. Therefore, this paper proposes a UMTS-WLAN interworking architecture for Quality of Service (QoS). The proposed architecture is based on tight coupling and dynamically guarantees QoS by the mobility prediction method. The proposed architecture is simulated by ns-2. Performance experimental results show that the proposed architecture reduces the handover dropping probability comparing with the existing method and enhances the amount of receiving packets comparing with the method without guaranteeing QoS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2709-2734
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• 2020

The growing demand to make wireless data services 5G compatible has necessitated the development of an energy-efficient approach for an effective new wireless environment. In this paper, we first propose a cognitive sensor node (CSN) based game theory for deriving energy via a primary user-transmitted radio frequency signal. Cognitive users' time was segmented into three phases based on a time switching protocol: energy harvest, spectrum sensing and data transmission. The proposed model chooses the optimal energy-harvesting phase as the effected factor. We further propose a distributed energy-harvesting model as a utility function via pricing techniques. The model is a non-cooperative game where players can increase their net benefit in a selfish manner. Here, the price is described as a function pertaining to transmit power, which proves that the proposed energy harvest game includes Nash Equilibrium and is also unique. The best response algorithm is used to achieve the green connection between players. As a result, the results obtained from the proposed model and algorithm show the advantages as well as the effectiveness of the proposed study. Moreover, energy consumption was reduced significantly (12%) compared to the benchmark algorithm because the proposed algorithm succeeded in delivering energy in micro which is much better compared to previous studies. Considering the reduction and improvement in power consumption, we could say the proposed model is suitable for the next wireless environment represented in 5G.

• Fire Science and Engineering
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• v.31 no.5
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• pp.117-122
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• 2017

The absence of fire fighters' connection to communication can bring about increased loss of life due to errors and delays in rescue and actions and danger to their own safety. Therefore, when communication infrastructure has been destroyed in an enclosed space, it is necessary to set up an emergency wire or wireless telecommunication environment to fire fighting and to secure safer environment to deal with the disaster by checking the location of fire fighters. In this research, for the establishment communication environment in an enclosed inside using Ultra-Wide Band (UWB) wireless communication network, the performance of communication position determination of a single UWB communication module was evaluated regarding 6 kinds of indoor surroundings. When the communication distance in an indoor environment of each 6 channels bandwidth of UWB communication frequency was measured, the results were as follows: the open space (Ave. 15.5 m, Max. 20 m), the corridor (Ave. 17.33 m, Max 20 m), inside retaining home furnishings (Ave. 15.3 m, Max. 20 m), vertical stairs (Ave. 4.33 m, Max. 6 m), horizontal space with a closed fire door (Ave. 6.5 m, Max. 17 m). It was also found out that the communication function and the distance function were best in the frequency range from 6489.6 to 1081.6 MHz by 7 Ch. Accordingly, the establishment of communication environment in an enclosed space is judged to be possible when UWB communication module is set up at 20 m apart and multiple channels are used.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.242-246
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• 2005

RFID(Radio Frequency Identification) which is emerging from a change in digital convergence paradigm and recently rapidly advancing throughout the overall society is the core technology based on Ubiquitous network. In other words, This is a technology to identify the information of the object and recognize the situation by attaching electrical tag to an object and using Reader that can read the information of the object. With the emergence of the technology, it has turned the existing maintenance of the product into the network and intelligence of the product control by using the bar cord to maintain the product and will lead a revolution throughout overall society by affecting the fields of distribution and product maintenance as well as those of medicines, chemicals and food which the electrical tag can be attached to. his paper shows that utilizing the Bluetooth which is a local wireless telecommunication in the standalone imbedded system can implement the piconet configuration among the Readers and the data telecommunication with the main server.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.45-48
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• 2004

RFID(Radio Frequency Identification) which is emerging from a change in digital convergence paradigm and recently rapidly advancing throughout the overall society is the core technology based on Ubiquitous network. In other words, This is a technology to identify the information of the object and recognize the situation by attaching electrical tag to an object and using Reader that can read the information of the object. With the emergence of the technology, it has turned the existing maintenance of the product into the network and intelligence of the product control by using the bar cord to maintain the product and will lead a revolution throughout overall society by affecting the fields of distribution and product maintenance as well as those of medicines, chemicals and food which the electrical tag can be attached to. this paper shows that utilizing the Bluetooth which is a local wireless telecommunication in the standalone imbedded system can implement the piconet configuration among the Readers and the data telecommunication with the main server